Except for differences in the trichomes, Alyssum canescens and A. tenuifolium overlap in plant height, petal length, and seed size, and they are sometimes separated with difficulty. A critical field study in parts of their ranges where they overlap, especially in Nei Mongol, Mongolia, and Siberia, is needed in order to reach a better understanding of their limits. Hybridization between the two species (Botschantzev, Bot. Zhurn. (Moscow & Leningrad) 44: 1486. 1959) was suggested, but no experimental work supports that hypothesis.

Alyssum tenuifolium was not listed in FRPS but was recorded for China (as Ptilotrichum tenuifolium) in Fl. Intramongol. (ed. 2, 2: 648. 1990). Several collections from Nei Mongol were examined by the present authors, including Roerich Expedition 375 (US) and Petrov s.n. (LE). Another species, P. dahuricum Peschkova (Novosti Sist. Vyssh. Rast. 15: 230. 1979), if indeed distinct from A. tenuifolium, was said to occur in China (Fl. Siberiae 7: 107. 1994), but the present authors have seen no Chinese material.